[Blindsight]

It probably doesn't make all that much difference with steroid based hormones like you're talking about. The molecules themselves won't break down easily in a reasonable temperature range. With peptide hormones (e.g. hgh, igf1, hcg), you really do have a narrow range of temperatures before they start degrading.

If your gear is fairly highly concentrated, keeping it too cold may cause precipitation, although I've never experienced this personally. I don't think warmer temps will affect it quite as much, although I wouldn't leave it in the car in the middle of summer in the south.